We study finite-time Landau-Zener transitions at a singlet-triplet level crossing in a GaAs double quantum dot, both experimentally and theoretically. Sweeps across the anticrossing in the high driving speed limit result in oscillations with a small visibility. Here we demonstrate how to increase the oscillation visibility while keeping sweep times shorter than T2* using a tailored pulse with a detuning dependent level velocity. Our results show an improvement of a factor of -2.9 for the oscillation visibility. In particular, we were able to obtain a visibility of -0.5 for Stückelberg oscillations, which demonstrates the creation of an equally weighted superposition of the qubit states.

2013-10-11T07:47:42ZengCoherent Adiabatic Spin Control in the Presence of Charge Noise Using Tailored Pulses2013-10-11T07:47:42ZGossard, Arthur C.We study finite-time Landau-Zener transitions at a singlet-triplet level crossing in a GaAs double quantum dot, both experimentally and theoretically. Sweeps across the anticrossing in the high driving speed limit result in oscillations with a small visibility. Here we demonstrate how to increase the oscillation visibility while keeping sweep times shorter than T<sub>2</sub><sup>*</sup> using a tailored pulse with a detuning dependent level velocity. Our results show an improvement of a factor of -2.9 for the oscillation visibility. In particular, we were able to obtain a visibility of -0.5 for Stückelberg oscillations, which demonstrates the creation of an equally weighted superposition of the qubit states.Lu, HongBurkard, GuidoGossard, Arthur C.deposit-licensePetta, Jason R.2013Ribeiro, HugoPhysical Review Letters ; 110 (2013), 8. - 086804Ribeiro, HugoPetta, Jason R.Lu, HongBurkard, Guido